LXR linux/arch/alpha/include/asm/xchg.h

   1#ifndef _ALPHA_CMPXCHG_H
   2#error Do not include xchg.h directly!
   3#else
   4/*
   5 * xchg/xchg_local and cmpxchg/cmpxchg_local share the same code
   6 * except that local version do not have the expensive memory barrier.
   7 * So this file is included twice from asm/cmpxchg.h.
   8 */
   9
  10/*
  11 * Atomic exchange.
  12 * Since it can be used to implement critical sections
  13 * it must clobber "memory" (also for interrupts in UP).
  14 */
  15
  16static inline unsigned long
  17____xchg(_u8, volatile char *m, unsigned long val)
  18{
  19        unsigned long ret, tmp, addr64;
  20
  21        __asm__ __volatile__(
  22        "       andnot  %4,7,%3\n"
  23        "       insbl   %1,%4,%1\n"
  24        "1:     ldq_l   %2,0(%3)\n"
  25        "       extbl   %2,%4,%0\n"
  26        "       mskbl   %2,%4,%2\n"
  27        "       or      %1,%2,%2\n"
  28        "       stq_c   %2,0(%3)\n"
  29        "       beq     %2,2f\n"
  30                __ASM__MB
  31        ".subsection 2\n"
  32        "2:     br      1b\n"
  33        ".previous"
  34        : "=&r" (ret), "=&r" (val), "=&r" (tmp), "=&r" (addr64)
  35        : "r" ((long)m), "1" (val) : "memory");
  36
  37        return ret;
  38}
  39
  40static inline unsigned long
  41____xchg(_u16, volatile short *m, unsigned long val)
  42{
  43        unsigned long ret, tmp, addr64;
  44
  45        __asm__ __volatile__(
  46        "       andnot  %4,7,%3\n"
  47        "       inswl   %1,%4,%1\n"
  48        "1:     ldq_l   %2,0(%3)\n"
  49        "       extwl   %2,%4,%0\n"
  50        "       mskwl   %2,%4,%2\n"
  51        "       or      %1,%2,%2\n"
  52        "       stq_c   %2,0(%3)\n"
  53        "       beq     %2,2f\n"
  54                __ASM__MB
  55        ".subsection 2\n"
  56        "2:     br      1b\n"
  57        ".previous"
  58        : "=&r" (ret), "=&r" (val), "=&r" (tmp), "=&r" (addr64)
  59        : "r" ((long)m), "1" (val) : "memory");
  60
  61        return ret;
  62}
  63
  64static inline unsigned long
  65____xchg(_u32, volatile int *m, unsigned long val)
  66{
  67        unsigned long dummy;
  68
  69        __asm__ __volatile__(
  70        "1:     ldl_l %0,%4\n"
  71        "       bis $31,%3,%1\n"
  72        "       stl_c %1,%2\n"
  73        "       beq %1,2f\n"
  74                __ASM__MB
  75        ".subsection 2\n"
  76        "2:     br 1b\n"
  77        ".previous"
  78        : "=&r" (val), "=&r" (dummy), "=m" (*m)
  79        : "rI" (val), "m" (*m) : "memory");
  80
  81        return val;
  82}
  83
  84static inline unsigned long
  85____xchg(_u64, volatile long *m, unsigned long val)
  86{
  87        unsigned long dummy;
  88
  89        __asm__ __volatile__(
  90        "1:     ldq_l %0,%4\n"
  91        "       bis $31,%3,%1\n"
  92        "       stq_c %1,%2\n"
  93        "       beq %1,2f\n"
  94                __ASM__MB
  95        ".subsection 2\n"
  96        "2:     br 1b\n"
  97        ".previous"
  98        : "=&r" (val), "=&r" (dummy), "=m" (*m)
  99        : "rI" (val), "m" (*m) : "memory");
 100
 101        return val;
 102}
 103
 104/* This function doesn't exist, so you'll get a linker error
 105   if something tries to do an invalid xchg().  */
 106extern void __xchg_called_with_bad_pointer(void);
 107
 108static __always_inline unsigned long
 109____xchg(, volatile void *ptr, unsigned long x, int size)
 110{
 111        switch (size) {
 112                case 1:
 113                        return ____xchg(_u8, ptr, x);
 114                case 2:
 115                        return ____xchg(_u16, ptr, x);
 116                case 4:
 117                        return ____xchg(_u32, ptr, x);
 118                case 8:
 119                        return ____xchg(_u64, ptr, x);
 120        }
 121        __xchg_called_with_bad_pointer();
 122        return x;
 123}
 124
 125/*
 126 * Atomic compare and exchange.  Compare OLD with MEM, if identical,
 127 * store NEW in MEM.  Return the initial value in MEM.  Success is
 128 * indicated by comparing RETURN with OLD.
 129 *
 130 * The memory barrier should be placed in SMP only when we actually
 131 * make the change. If we don't change anything (so if the returned
 132 * prev is equal to old) then we aren't acquiring anything new and
 133 * we don't need any memory barrier as far I can tell.
 134 */
 135
 136static inline unsigned long
 137____cmpxchg(_u8, volatile char *m, unsigned char old, unsigned char new)
 138{
 139        unsigned long prev, tmp, cmp, addr64;
 140
 141        __asm__ __volatile__(
 142        "       andnot  %5,7,%4\n"
 143        "       insbl   %1,%5,%1\n"
 144        "1:     ldq_l   %2,0(%4)\n"
 145        "       extbl   %2,%5,%0\n"
 146        "       cmpeq   %0,%6,%3\n"
 147        "       beq     %3,2f\n"
 148        "       mskbl   %2,%5,%2\n"
 149        "       or      %1,%2,%2\n"
 150        "       stq_c   %2,0(%4)\n"
 151        "       beq     %2,3f\n"
 152                __ASM__MB
 153        "2:\n"
 154        ".subsection 2\n"
 155        "3:     br      1b\n"
 156        ".previous"
 157        : "=&r" (prev), "=&r" (new), "=&r" (tmp), "=&r" (cmp), "=&r" (addr64)
 158        : "r" ((long)m), "Ir" (old), "1" (new) : "memory");
 159
 160        return prev;
 161}
 162
 163static inline unsigned long
 164____cmpxchg(_u16, volatile short *m, unsigned short old, unsigned short new)
 165{
 166        unsigned long prev, tmp, cmp, addr64;
 167
 168        __asm__ __volatile__(
 169        "       andnot  %5,7,%4\n"
 170        "       inswl   %1,%5,%1\n"
 171        "1:     ldq_l   %2,0(%4)\n"
 172        "       extwl   %2,%5,%0\n"
 173        "       cmpeq   %0,%6,%3\n"
 174        "       beq     %3,2f\n"
 175        "       mskwl   %2,%5,%2\n"
 176        "       or      %1,%2,%2\n"
 177        "       stq_c   %2,0(%4)\n"
 178        "       beq     %2,3f\n"
 179                __ASM__MB
 180        "2:\n"
 181        ".subsection 2\n"
 182        "3:     br      1b\n"
 183        ".previous"
 184        : "=&r" (prev), "=&r" (new), "=&r" (tmp), "=&r" (cmp), "=&r" (addr64)
 185        : "r" ((long)m), "Ir" (old), "1" (new) : "memory");
 186
 187        return prev;
 188}
 189
 190static inline unsigned long
 191____cmpxchg(_u32, volatile int *m, int old, int new)
 192{
 193        unsigned long prev, cmp;
 194
 195        __asm__ __volatile__(
 196        "1:     ldl_l %0,%5\n"
 197        "       cmpeq %0,%3,%1\n"
 198        "       beq %1,2f\n"
 199        "       mov %4,%1\n"
 200        "       stl_c %1,%2\n"
 201        "       beq %1,3f\n"
 202                __ASM__MB
 203        "2:\n"
 204        ".subsection 2\n"
 205        "3:     br 1b\n"
 206        ".previous"
 207        : "=&r"(prev), "=&r"(cmp), "=m"(*m)
 208        : "r"((long) old), "r"(new), "m"(*m) : "memory");
 209
 210        return prev;
 211}
 212
 213static inline unsigned long
 214____cmpxchg(_u64, volatile long *m, unsigned long old, unsigned long new)
 215{
 216        unsigned long prev, cmp;
 217
 218        __asm__ __volatile__(
 219        "1:     ldq_l %0,%5\n"
 220        "       cmpeq %0,%3,%1\n"
 221        "       beq %1,2f\n"
 222        "       mov %4,%1\n"
 223        "       stq_c %1,%2\n"
 224        "       beq %1,3f\n"
 225                __ASM__MB
 226        "2:\n"
 227        ".subsection 2\n"
 228        "3:     br 1b\n"
 229        ".previous"
 230        : "=&r"(prev), "=&r"(cmp), "=m"(*m)
 231        : "r"((long) old), "r"(new), "m"(*m) : "memory");
 232
 233        return prev;
 234}
 235
 236/* This function doesn't exist, so you'll get a linker error
 237   if something tries to do an invalid cmpxchg().  */
 238extern void __cmpxchg_called_with_bad_pointer(void);
 239
 240static __always_inline unsigned long
 241____cmpxchg(, volatile void *ptr, unsigned long old, unsigned long new,
 242              int size)
 243{
 244        switch (size) {
 245                case 1:
 246                        return ____cmpxchg(_u8, ptr, old, new);
 247                case 2:
 248                        return ____cmpxchg(_u16, ptr, old, new);
 249                case 4:
 250                        return ____cmpxchg(_u32, ptr, old, new);
 251                case 8:
 252                        return ____cmpxchg(_u64, ptr, old, new);
 253        }
 254        __cmpxchg_called_with_bad_pointer();
 255        return old;
 256}
 257
 258#endif
 259